176 BULLETIN 43, UNITED STATES NATIONAL MUSEUM. 



makes no allusion to M. glaucinus, but institutes comparisons with M. 

 perotis, from which it is undoubtedly distinct. In the absence of exact 

 information respecting M. gJancinus^ I have concluded to adopt pro- 

 visionally Mr. Merriam's name as one based upon the study of the adult. 

 Careful comparisons with 31. glaucmns must be made before its validity 

 is established. 



M. (jJaueinns is stated by Dobson to be light broAvn at the base of the 

 hairs, then chestnut brown, the extreme tips grayish, so that the upiicr 

 surface appears altogether gray. The colors of M. californicus are 

 within the group of the grays, and it is tenable that the basal shade 

 may be variable within specific limits and pass from chestnut to buff 

 and thence to white buff. Be this as it may, the coloration may be dis- 

 carded in the diagnosis, and the important specific characters made to 

 include the emargination on the posterior border of the auricle (which 

 is said by Dobson to be absent in M. glaucimis), the presence of a tu- 

 bercle on the interauricular membrane, and in the first upper premolar 

 being central in the space between the canine and second premolar. 



The tragus in M. glaucinus, according to Dobson, is 0.12 (3.J'"^^), while 

 in M. californicus it is -4'"", a difference so slight as to come within the 

 range of personal error. 



The difference in the measurements of the body and limbs is not 

 greater than those between specimens of M. pcrotis in the Cambridge 

 collection and those of the British Museum series made by Dobson. 



On the dorsum the hair has sooty-ash tips, varying to a light buff 

 or whitish; thus the hair is of two colors. The greater portion is a 

 shade of white. The tips appear to be less differently colored from the 

 shaft over the loin than elsewhere. On the venter the color is lighter, 

 the tips of the hairs are less sooty, but still ashy. 



On the membranes the hair covers the basal half of the ear dorsally; 

 it.extends from the proximal third of the humerus to near the knee, 

 and on the interfemoral membrane at the basal third. On the venter 

 the* hair is about of the sanie distribution as above, but they do not 

 reach so far along the thigh, and more is found along the forearm. 



A thin line of dark uuicolored hair is seen along the upper border of 

 the proximal third of the forearm in advance of the elboAv; a second 

 much larger line of similar hair extends from the proximal third of the 

 forearm to the wrist, and a white defined patch overlies the carpal i)or- 

 tion of the fourth digital interspace. 



Membranes. — The prebrachium not volant beyond the junction of the 

 proximal to the middle third of tlte forearm. The wing membrane is 

 attached to the distal fourth of the leg. No. 19088, U. S. N. M., female, 

 has a rudimentary gular pouch. Auricle ample, one-third longer than 

 head, nearly circular, with a broad, shallow excavation on outer mar- 

 gin; the keel long, nearly reaching the notch, and is slightly folded for- 

 ward. The hem begins at the posterior emargination, becomes gradu- 

 ally convex, but narrows opposite the external basal ridge, crosses the 



